The goal is to develop a long term human myeloma cell line which will provide valuable substrates for subcategorizing B cell malignancies, for generating human derived monoclonal antibodies which may become major diagnostic and/or therapeutic tools and for understanding the normal and abnormal process of human B cell maturation. A long term plasma cell line, derived from a patient with multiple myeloma, will be characterized, subcloned and used as antigen in the genesis of mouse monoclonal antibodies directed against human plasma cells and/or human myeloma cells. The role of growth and differentiation factors in the maintenance of the long term line will be explored and attempts will be made to utilize such factors in establishing growth of other human myeloma cells.